Fluid conduit arrangement

ABSTRACT

1. THE METHOD OF PROVIDING A FLUID CONDUIT COMPRISING THE STEPS OF ARRANGING A PLURALITY OF ELONGATED MEMBERS SO AS TO DEFINE A SUBSTANTIALLY RECTANGULAR PATTERN HAVING OPEN SPACES THEREIN, POSITIONING A SUBSTANTIALLY FLAT AND RIGID STRIP AT EITHER END OF SAID PATTERN TO FORM A PART THEREOF, HOLDING SAID ELONGATED MEMBERS AND SAID STRIPS TOGETHER IN SAID PATTERN, SUPERIMPOSING A FLEXIBLE SHEET ON SAID ELONGATED MEMBERS TO SAID OPEN SPACES, THEN BENDING SAID ELONGATED MEMBERS, SAID SHEET AND SAID STRIPS IN A DIRECTION GENERALLY TRANSVERSE TO SAID STRIPS SO AS TO CAUSE SAID STRIPS AND ELONGATED MEMBERS TO BE GIVEN A PERMANENT SET SUCH THAT OPPOSITE EDGE PORTIONS OF SAID PATTERN ARE BROUGHT INTO ADJACENCY AND SAID SHEET, SAID STRIPS AND SAID ELONGATED MEMBERS DEFINE A PASSAGEWAY COLLECTIVELY THERETHROUGH AND SAID STRIPS EXTEND AROUND THE ENDS OF SAID PASSAGEWAY, AND ATTACHING TOGETHER SAID EDGE PORTIONS OF SAID PATTERN WHEN SO BENT, THEREBY PROVIDING A FLUID CONDUIT,   D R A W I N G

0v. 5', 1914 J. F. KRAMER 3,846,083

FLUID CONDUIT ARRANGEMENT Original Filed April 29, 1971 7 Sheets-Sheet 11914 J; F. KRAMER 3,846,083

FLUID CONDUIT ARRANGEMENT 7 Sheets-Sheet 2 Original Filed April 29, 1971J. F. KRAMER NDUIT ARRANGEMENT Original Filed April 29, 1.971

Mum I Nov. 5, IQ'FQ J. F. KRAMER 3.

FLUID CO NDUII ARRANGEMENT Original Filed April 29, 1971 7 SheetsSheet 4Ln I l' J7//,/5,

iimmzmiliimmliiiL N J. F. KRAM ER 3,846,083

FLUID CONDUIT ARRANGEMENT Original Filed April 29, 1971 7 Sheets-Sheet 5Nov. 5, m4 ,1. F. KRAMER 3,846,083

FLUID connurr ARRANGEMENT Original Filed April 29, 1971 7 Sheets-Sheet 6Nov. 5, 1914 F, KRAMER 3,846,083

FLUID CONDUIT ARRANGEMENT Original Filed April 29, 1971 7 Sheets-Sheet'7 i 5? i r 14 United States Patent t) 3,846,083 FLUID CONDUITARRANGEMENT John F. Kramer, Fullerton, Calif. (2235 W. Broadway,

Suite H-102, Anaheim, Calif. 92804) Application Apr. 29, 1971, Ser. No.138,685, now Patent No. 3,726,322, which is a continuation-in-part ofabandoned application Ser. No. 826,358, May 21, 1969. Divided and thisapplication Apr. 9, 1973, Ser. No.

Int. Cl. B21d 53/00 US. Cl. 29-157 R 9 Claims ABSTRACT OF THE DISCLOSUREThe arrangement of this invention for providing a fluid conduit includesa plurality of spaced parallel elongated elements positioned in a flatrectangular pattern, a means for holding the elements in the pattern,strips of flat material at the ends, and a sheet of material overlyingthe elongated members, which is formed into a fluid conduit by effectingappropriate bends in the elongated elements and end strips intermediatethe side edges to bring the side edges into adjacency where they arejoined. The bends may be of diflerent configurations at the two ends ofthe unit. When the elongated elements are in spaced parallelismtransverse to the unit, the resulting conduit will be flexible and maybe bent to form an elbow, or into other shape. When longitudinallyextending elongated elements are included, rigidity is imparted at thelocations of such elements. Interlocking arrangements may be provided tosecure together the side edges, or these edges may be welded orotherwise secured. Two layers of sheet material may be used, bondedtogether and to the inner and outer surfaces of the elongated elements,and insulation may be provided over the outside.

REFERENCE TO RELATED APPLICATION This is a division of application Ser.No. 138,685, filed Apr. 29, 1971, now Pat. No. 3,726,322, which is acontinuation-in-part of my copending patent application Ser. No.826,358, filed May 21, 1969, for Fluid Conduit Arrangement, nowabandoned.

BACKGROUND OF INVENTION Field of the Invention This invention relates toa fluid conduit and the method of producing the fluid conduit.

Description of Prior Art provide adaptability, there are ducts of aflexible nature which include a spiral of wire beneath a coveringmaterial. These are relatively expensive and, again, must be made up ata factory and, as bulky items, they require a large volume for storageand shipment.

SUMMARY OF THE INVENTION This invention provides an improved arrangementfor providing air ducts and fittings which may be flexible or rigid. Inone embodiment, a flat assembly is provided that includes substantiallyrigid elements in the form of sheet metal strips and a plurality ofintermediate spaced parallel wires that define a rectangular pattern.Flexible fluidimpervious sheet material overlies the wires. The assemblyis formed into a duct or fitting by bending the wires and end stripstransversely so that they are given a permanent set, and the margins ofthe pattern are brought into adjacency where they are attached andsealed. The resulting fluid conduit is deflectable to provide a flexibleduct section. Moreover, it may be bent to form an elbow of any desiredangularity.

In forming the duct section, the opposite ends of the unit may be bentto different configurations so that it may be used to interconnect ductsof different proportions. It may be square on one end and rectangular onthe other, may have rectangular ends of different proportions, or may becircular or of other shape at one or both ends. The unit is economicalto manufacture, and normally is sold, shipped and stored in its flatcondition. This offers an enormous saving in storage volume andfacilitates transportation of the items. It is a simple matter to bendthe unit on a brake or by other means to form the duct section orfitting on the job. This operation may be performed by relativelyunskilled personnel.

With the addition of spaced wires extending longitudinally for part orall of the length of the duct, rigidity can be imparted to it in theportions where the longitudinal wires are present. Various standardattaching means may be provided for securing the margins of the pattern,which may be either by an interlocking arrangement or by welding orotherwise. The addition of a transverse sheet metal strip intermediatethe ends of the flexible arrangement will provide a means for limitingthe angularity that can be imparted to an elbow, so that there is nodanger of cansing the duct to have such a sharp bend that there will bean undue restriction to the flow of the fluid. Also, this permits theunit to be cut in two at the central strip to produce two 45 elbows orone elbow. It further provides a means for mounting turning vanes toassist the flow of the fluid.

When the unit is produced with longitudinal wires to provide a rigidunit and is to be formed into a rectangular or square shape, the lockingarrangement may be at a corner, which means that only three bends of theflat pattern are necessitated.

The covering that is provided over the wires may be of any of a widevariety of materials, such as vinyl sheet material, scrim, foil, etc.Frequently, a layer of appropriate insulation will be included over thesheet material, which then, in turn, may be encased beneath anotherlayer of sheet material. If desired, an additional layer of sheetmaterial may cover the wires, or a protective coating or the like may beincluded on the wires in the inside of the duct, allowing it to transmitcorrosive materials.

When two layers of flexible sheet material are provided, they may beused to hold the transverse members of the pattern in a unitaryassembly. An adhesive is employed to bond the sheets to the two sides ofthe pattern, forming an attachment to the wires and end strips. Thesheets are adhesively secured to each other in the spaces between theadjacent wires. An added advantage from the use of two flexible sheetsis that, if one should become punctured or torn, such as during theformation of the duct from the fiat pattern, the other layer willpreserve the integrity of the passageway and leakage will be avoided.When only transverse wires are included in the rectangular pattern andthere are no rigid elements extending lengthwise to preclude bending ofthe duct, it possesses flexibility from one end to the other. Hence, itcan be deflected to virtually any contour desired.

An object of this invention is to provide an improved means of producinga fluid conduit.

Another object of this invention is to provide an arrangement by which afluid conduit may be produced rapidly and easily by relatively unskilledpersonnel.

A further object of this invention is to provide an arrangement by whicha flat unit, which occupies little volume during transportation andstorage, may be bent on the job site to provide a fluid conduit tailoredto suit the conditions at hand.

An additional object of this invention is to provide an arrangementadapted to produce a single relatively large elbow or which can besevered to provide a duality of smaller elbows.

Yet another object of this invention is to provide an arrangement whichcan provide a fluid conduit having different configurations at its twoends.

A further object of this invention is to provide an arrangement adaptedto provide fluid conduits with different exterior coverings, and whichcan avoid the need for a separate layer of insulation.

Another object of this invention is to provide an arrangement to produceboth flexible and rigid fluid H conduits.

A still further object of this invention is to provide an arrangement bywhich a wide variety of duct shapes and proportions may be produced froma single flat pattern.

These and other objects will become apparent from the following detaileddescription taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a unitprepared for subsequent bending to form an elbow or a duct;

FIG. 2 is an enlarged sectional view taken along line 22 of "FIG. 1;

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a perspective view of a 90 elbow produced from the unit ofFIG. 1;

FIG. 5 is an enlarged end elevational view of the seam that connects theedges of the elbow;

FIG. 6 is a schematic plan view of the unit of FIG. 1 indicating thelocations of the bend lines;

FIG. 7 is a perspective view of a duct section produced by bending theunit as indicated in FIG. 6;

FIG. 8 is a view similar to FIG. 6, but with bend lines shown forproviding a duct section of different proportions at its opposite ends;

FIG. 9 is a perspective view of the duct section produced from the unitof FIG. 8;

FIG. 10 is a plan view of a unit utilizing a continuous length of wireinstead of a number of shorter wires;

FIG. 11 is a plan view of a modified form of the unit for producing aduct section rigid at its ends;

FIG. 12 is an enlarged sectional view taken along line 12-12 of FIG. 11;

FIG. 13 is a perspective view of a duct section produced from the unitof FIG. 11;

FIG. 14 is an enlarged fragmentary sectional view of the seam of theduct section of FIG. 13;

FIG. 15 is a plan view of a modification of the unit of FIG. 11, whichis flexible throughout its length;

FIG. 16 is a plan view of a further modification of the unit of FIG. 11which will produce a duct section rigid at the center and flexible atthe ends;

FIG. 17 is a plan view of another embodiment of a unit to provide arigid duct section;

FIG. 18 is an enlarged sectional view taken along line 18-18 of FIG. 17;

FIG. 19 is an enlarged fragmentary sectional view of the seam portion ofa duct produced from the unit of FIG. 17;

FIG. 20 is an enlarged fragmentary sectional view of the seam portionwhere the duct section is made circular in cross section;

FIG. 21 is a perspective view, partially in section, of a unit forproducing a duct in which the transverse elements are held betweensuperimposed layers of sheet material bonded together;

FIG. 22 is an enlarged fragmentary view of one end portion of thepattern of FIG. 21;

FIG. 23 is a perspective view of a duct section pro duced from thepattern of FIG. 21;

FIG. 24 is a fragmentary perspective view of a modification of thepattern of FIGS. 21 and 22 in which the projecting flap is integral withone of the sheets that overlies the wires;

FIG. 25 is a fragmentary perspective view of a duct produced from thepattern of FIG. 24; and

FIG. 26 is a fragmentary perspective view of a duct similar to that ofFIG. 25 in which a separate strip of adhesive tape is used in lieu of anintegral projecting flap.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The unit 10 shown in FIGS. 1, 2and 3 may be used for forming flexible elbow fittings. This unit is arelatively flat, rectangular framework made up of sheet metal, wires anda covering material. The sheet metal parts, typically of galvanizediron, include parallel side edge pieces 11 and 12 which at their endsare interconnected by sheet metal strips 13 and 14 that are at rightangles to them. An additional and slightly wider metal strip 15, whichis parallel to the strips 13 and 14, interconnects the central portionsof the side pieces 11 and 12. The connections of the elements 13, 14 and15' to the side edge strips 11 and 12 may be accomplished byspot-welding.

Also extending between the side edge pieces 11 and 12 are elongatedelements 16 that fit in the spaces between the central metal strip 15and the end metal strips 13 and 14. The elongated members 16 may be ofvarious shapes, such as wires, rods, bars or strips. Desirable resultsmay be achieved through the use of steel rods having a diameter of aboutinch. The members 16 are spaced apart and parallel to the metal strips13, 14 and 15, being held in this relationship by welded connections tothe side strips 11 and 12.

On one side of the assembly 10 is a covering 17 which closes out theopen spaces between the elongated members 16 so that, when the fittingis completed, it can transmit fluid. For air conditioning or heatinguse, the covering 17 normally will include a layer of insulation. Thus,as seen in FIG. 2, the covering 17 is made up of a blanket of glassfibers 18 enclosed between vinyl sheets 19 and 20. The vinyl sheet 19 ispositioned next to the members 16 and extends outwardly over the edgestrips 11 and 12 to which it is bonded. The outer vinyl sheet 20overlaps the margin of the sheet 19 and also is bonded to the edgestrips 11 and 12. A similar arrangement is provided at the outer endstrips 13 and 14 where, again, the vinyl sheets 19 and 20* extend overthese members and are bonded to them. The glass fiber blanket 18terminates just beyond the inner edges of the metal strips 11, 12, 13and 14, although it may be extended to overlap further. With theinclusion of the insulation 18, the need for separately insulating thecompleted elbow may be avoided. Also, this will have the beneficialeffect of reducing sound transmission through the fitting.

The outer margins of the edge strips 11 and 12 are pro vided with anattaching means allowing them to be readily secured together when thefitting is formed. In the embodiment shown, Where a double-seam joint isto be produced, there are doubled-over margins 22 and 23 on the sideedge strips 11 and 12. The marginal portion 22 is formed on one side ofthe strip 11, while the marginal portion 23 is bent toward the oppositeside of the strip 12, as best seen in FIG. 2. Other arrangements may beprovided for holding the adjacent edges of the edge strips 11 and 12 inthe desired relationship, such as self-sealing adhesive tape, welding,or any other means.

When a fitting such as a elbow is to be produced it is merely necessaryto provide bends in the unit and thereafter to secure the margins of theedge strips 11 and 12. The bends are generally transverse to the strips13, 14 and and are readily made on a brake. In accomplishing theattachment of the margins, the double-over portions 22 and 23 are fittedone inside the other to provide an interlock, as seen in FIG. 5. Afterthe margins 22 and 23 of the edge strips 11 and 12 are fastenedtogether, the resulting conduit then may be bent to provide a 90 elbowas illustrated in FIG. 4, or an elbow of any desired angularity. Whenthe spacing between the end strips is increased, the elbow may traverseup to 360. When the elbow is formed, the edge strips 11 and 12 lie alongthe outside or heel of the elbow, and are bent about an axis transverseto them. The members 16, extending transversely of the edge strips 11and 12, do not interfere with the bending of the conduit to define theelbow. The elbow retains its shape because of the curvature imparted tothe edge strips 11 and 12. The end strips 13 and 14 in the completedelbow serve as a means of attachment to the connecting duct sections.

The arrangement for providing an elbow of square cross section, such asshown in FIG. 4, is illustrated schematically in FIGS. 6 and 7. There,lines 25, 26, 27 and 28 represent the locations where the bends are madein the members 16 and end members 13 and 14 to result in a short duct ofsquare cross section. The bends are all parallel to the margins 22 and23 of the flat pattern. There is equal spacing between the adjacent bendlines 25, 26, 27 and 28. Approximately half of this spacing existsbetween the outer bend lines 25 and 28 and the marginal portions, with alittle additional being provided to allow for the overlap where theconnecting seam is produced. With right-angle bends made at theselocations, the duct of FIG. 7 is produced. Subsequently, this duct isbent to form the elbow.

The invention is not limited to the production of fittings of squarecross section. Instead, they may be rectangular, circular, elliptical,hexagonal or any other shape desired. Moreover, they may be made todifferent configurations at the two ends of the fitting. For example, afitting may be of one proportion on one end, such as a rectangular shapeinches by 16' inches, and at the opposite end of entirely differentproportions, such as 29 inches by 7 inches, or it may be square orrectangular at one end and circular at the other. The variations andcombinations almost are limitless. From an assortment of sizes of theunit 10, therefore, hundreds of different elbow sizes and shapes may beproduced. The fittings may be completed quite easily in the field,tailored to the situation at hand, and made without skilled sheet metalmechanics. Prior to the fabrication of the fittings, the flat patterns10 occupy little space for shipment and storage.

If desired, the side edge strips 11 and 12, the elongated members 16 andthe end strips 13 and 14 may be formed of a plastic material, such aspolyvinyl chloride or from any kind of material having similar physicalcharacteristics. If the material is plastic, it should be thermoplasticso that it can be bent into the desired configuration by heat and forceand thereafter retain such configuration upon cooling. The elongatedmembers 16 may be secured to the side edge strips 11 and 12 by anysuitable solvent cement. As stated above, all of the components may beformed of any desirable material so long as the material possesses thedesired physical characteristics, such as the ability to be bent intodifferent configurations and to retain such configuration.

In FIG. 8, the bend pattern is illustrated for producing a duct sectionas shown in FIG. 9, which is square at one end and rectangular at theother. The bend lines 31, 32, 33 and-34 are not parallel to the outermargins in this instance, but, instead, are inclined. The alternate bendlines 31 and 33 are parallel, while the other set 32 and 34 also areparallel. The spacing of the bend lines at one edge of the pattern, thebottom as shown in FIG. 8, is equal except for the half spacing at theside edges, this being the location where the square shape is to beprovided. At the opposite end, however, there is a wide spacing betweenthe ends of the lines 31 and 32 and between the lines 33 and 34. Theshorter spacing between the lines 32 and 33 is substantially double thatbetween the line 31 in one side margin and line 34 in the other sidemargin. Therefore, when bends are effected along the lines 31, 32, 33and 34, and the margins are secured together, the duct unit of FIG. 9 isproduced. This then may be bent to provide a suitable elbow.

While described above as including a covering unit of vinyl sheetmaterial and glass fiber blanket, many other coverings may be utilized.The covering may be of material having no rigidity because the membersbeneath it provide it with support so that it maintains the intendedshape of the fitting. Other materials that may be used include scrim,foil, glass cloth and neoprene or vinyl-coated or impregnated fabrics.Any suitable materials or combinations of materials may be employed tosatisfy particular conditions. Generally, it is unnecessary to cover themembers 16 on the inside of the fitting. However, sheet material may beincluded there, if desired, to pro- Vide an interior lining. The members16 may be plastic coated for protection in the event corrosive fluidsare to be transmitted.

When the fitting is produced as described above, there is, of course, asheet metal section intermediate its ends at the location of the centralmetal strip 15. It offers several advantages to the completed fitting.The presence of the central strip 15 prevents the user from forming abend in the elbow that is too sharp. Thus, the metal strip 15necessitates a radius for the completed elbow that is sufiicient toassure that the fitting will not provide an undue restriction to theflow of fluid through it. Also, the

metal strip 15 may be cut in two, permitting the creation of two 45elbows rather than a single 90 elbow. Additionally, with the metal strip15 in place, there is a location for attaching turning vanes to assistthe fluid flow around the elbow, if this is desired. It is apparent,however, that the fitting can be constructed without the use of thecentral metal strip 15, with the various assembly steps remainingunchanged.

In some instances, it may be desirable to provide a fitting thatconnects between ducts having diiferent outside perimeters. For example,one unit may have an outlet with an outside perimeter of 72 inches,while the second unit has an outlet with an outside perimeter of 54inches. In such a case, the end strip 13 would have a length of 72inches and the end strip 14 would have a length of 54 inches. The sideedge strips 11 and 12 would converge toward each other as they extendedbetween and connected the extremities of the end strip 13 to theextremities of the end strip 14. The elongated members 16 would be ofprogressively decreasing lengths toward the end strip 14 comparable tothe decreasing distance between the side edge strips 11 and 12.

In the modification of FIG. 10, there is an example of the flat patternwith the central strip omitted. Also, instead of utilizing a pluralityof individual elongated members connected to the end strips of the unit,a single element such as a length of wire 36 is employed. This wire islooped back and forth in an undulating pattern to provide parallelsections extending between the side strips 11 and 12. Hence, it providesthe equivalent of the individual members 16 and is formed into a fluidconduit the same as the embodiment previously described, varying only inthe manner of construction of the flat framework.

While described above as being applied to the fabrication of fittingssuch as 90 or 45 elbows, the arrangement of this invention is equallyadapted for constructing straight duct sections. The fiat pattern simplyis made longer between the end strips 13 and 14 when it is to be used asa duct section of normal length. Such ducts are produced as readily asthe fittings, and permit great flexibility in the installation as theymay be bent or deflected appropriately to avoid obstructions asinstalled on the job without the necessity for fabricating individualfittings to take care of this. Again, the ends of the ducts may havedifferent shapes.

The arrangement shown in FIGS. 11 and 12 provides a duct section whichis rigid at its ends but flexible in its intermediate portion. The flatpattern of the unit includes a plurality of spaced parallel elongatedmembers, such as wires or rods, 37 extending perpendicularly between andwelded to similar elongated end members 38 and 39. Shorter wires orsimilar members 40 are secured to the members 39 adjacent the left-handend as the device is shown in FIG. 11, forming a grid at that location.Similar shorter members 41, parallel to the end mem bers 38 and 39, arewelded to the right-hand members 37 to provide an additional grid.Welded to the two members 37 at the side edges are sheet metal strips 42and 43 at the left-hand and right-hand sides, respectively.

An appropriate covering material is on one side of the unit, which maybe of suitable composition as described above to satisfy particularconditions. As illustrated, particularly in FIG. 12, there is a vinylsheet 45 adjacent the members, beyond which is a glass fiber blanket 46along the outer surface of Which is a vinyl sheet 47. The vinyl sheets45 and 47 overlap and are bonded to the end strips 42 and 43 similar tothe way that the sheets 19 and 20 overlap and are bonded to the strips11, 12, 13 and 14 in the embodiment of FIGS. 1, 2 and 3. However, alongthe other edges at the members 38 and 39, the edges 48 and 49 of theglass fiber blanket 46 are left open. At one edge adjacent the member38, the sheet 47 extends beyond the member 38 to form a projecting flap50.

When the duct section is fabricated, the unit is shaped to a circular orother configuration as shown in FIG. 13. This brings the edges 48 and 49of the insulating blanket into adjacency. Also, the members 38 and 39are brought together and welded to form an attachment. Any othersuitable means, such as short pieces of readily deformable wire whichmay be wrapped around the adjacent members 38 and 39 and twisted, may beused to hold the members 38 and 39 in the desired position. With thistype of connection, the unit is more adapted for factory constructionthan for field assembly as for the embodiments utilizing a mechanicallocking arrangement. The projecting flap 50 of the outer sheet 47overlaps at the joint thereby formed to provide an appropriately sealedexterior. The duct produced in this manner is flexible intermediate itsend portions and rigid adjacent the ends. Wherever Wires 40 and 41 arepresent, the rigidity s found, while in between where only thetransverse members 37 are located the unit is bendable.

Where full flexibility along the length of the duct desired, it may beproduced as shown in FIG. 15. Here, the shorter wires 40 and 41 areomitted, leaving only the transverse members 37. Hence, when the members38 and 39 are welded together as the duct is fabricated, there are norigid elements extending lengthwise to preclude bending of the duct.Therefore, the duct possesses flexibility from one end to the other. Inthis arrangement, the wires 38 and 39 are of a gauge which permits theirdeflection in any direction as the duct is flexed, and these wires mayassume a corrugated configuration when on the inside of the bend.

In FIG. 16, the duct is constructed with only the transverse members 37adjacent the end strips 42 and 43. However, at the central portion,there are included shorter wires 52 extending lengthwise, or parallel tothe edge members 38 and 39. Hence, when this version is formed into acompleted duct, it is flexible at its end portions and rigid at itscentral part.

In the arrangement shown in FIGS. 17, 18 and 19, the flat patternincludes sheet metal end strips 54 and 55 spot-welded or otherwisesuitably secured to sheet metal edge strips 56 and 57. To these stripsare attached longitudinal and transverse elongated members 58 and 59,respectively, forming a grid. Again, a suitable material overlies oneside of the unit to provide the sealing medium, which may be a vinylsheets 60 and an outer sheet 61 with a layer of insulation 62 betweenthem. The margins of the strips 56 and 57 are bent to provide a.Pittsburgh lock to effect the attachment of these parts of the unit whenthe duct is formed. In providing this, the metal strip 56 has a flange64 bent at right angles to it. The margin of the other side strip 57 istwice doubled over to leave a short outwardly projecting flange 65,while providing an outwardly facing slot 66 along the margin of thestrip 57. When the duct is formed, the flange 64 of the margin strip 56is fitted into the slot 66. The flange 65 then is bent at right anglesto overlap the edge of the strip 56 and prevent the flange 64 fromescaping from the slot 66. This form of attachment, therefore, isadapted to be made at the corner of the completed duct when the unit isto be of square or rectangular cross section. With this location of theseam, the square or rectangular duct may be formed with only threebends, rather than four as in the previously described embodiment wherethe joint was effected in the flat portion of one side. With this typeof lock and the grid of cross wires as shown, the duct is a rigid unit.

The Pittsburgh lock also can be used as shown in FIG. 20 when a roundduct is to be provided from the pattern of FIG. 17. In that event, aflange 68 is provided on the edge strip 56, which is doubled over andparallel to the edge of the strip rather than being at right angles asdescribed above. This enables it to enter the receptacle 66 in themating portion of the lock without traversing a right-angle bend.

The wires intermediate the end strips of the flat pattern may be heldtogether effectively by a double layer of sheet material secured byadhesive, as illustrated in FIGS. 21 and 22. In this arrangement, as inthat of FIG. 15, full flexibility of the resulting duct is obtained.Accordingly, there are parallel wires 69 inter-mediate and parallel tosheet metal end strips 70 and 71, collectively forming a rectangularpattern, with the opposite end portions of the wires and strips being atthe opposite edges of the pattern. There are two sheets of flexiblematerial 72 and 73 covering the upper and lower portions, respectively,of the pattern as it is illustrated. The sheets 72 and 73 are secured tothe wires 69, and to each other intermediate the wires 69, by anadhesive 74. The edges of the sheets 72 and 73 overlap the end strips 70and 71 and are bonded to these elements by the adhesive 74.

In the event that it is desired to produce an insulated duct section, alayer of insulating material, together with a covering sheet, is appliedto one side of the pattern. The insulation is optional. In the exampleshown, there is a blanket 75 of suitable insulating material positionedadjacent the lower vinyl sheet 73. An outer layer 76 of vinyl covers theinsulation 75 and overlaps the marginal portions of the vinyl sheet 73to which it is bonded by additional adhesive 74. A strip 77 of the sheetmaterial, which may be similar to the flap 50 of FIGS. 11, 12 and 13, isincluded along one side edge of the pattern.

The pattern of FIG. 21 is formed into a completed duct, such as therectangular duct 78 shown in FIG. 23, by bending the wire 69 and the endstrips 70 and 71 transversely so as to give them a permanent set, withthe opposite edge portions of the pattent in adjacency so as to definethe shape of the duct. Then, the adjacent edge portions are securedtogether with the strip 77 extending over the outside of the joint andbonded to the adjacent outer surface of the duct assembly, eifecting aseal. When, as in the embodiment of FIG. 15, there are no rigid elementsextending lengthwise of the duct, it is fully flexible intermediate itsends, as indicated in phantom in FIG. 23.

The bonded sandwich construction provides an efiective means for holdingtogether the assembly of wires, strips and sheet material. This alsoresults in a safety factor to minimize the likelihood of leakage whenthe duct section is produced from the fiat pattern. If the outer sheetmaterial should become torn, the inner layer will remain intact toconfine the fluid being transmitted, which is of particular significancewhen the insulation 75 is omitted. When the adhesive 74 is anonhardening type, some relative movement between the sheets and wiresis permitted when the parts are bent to form the duct 78. This assistsin avoiding damage to the outer sheet.

In the embodiment of FIG. 24, the projecting flap 79 is integral withone of the flexible sheets 80 that overlies the wires 81 and the endstrips 82. A pressure-sensitive adhesive 83 may be used on the sheet 80and its flap 79, as well as on the inner surface of the other flexiblesheet 84. When the pattern of FIG. 24 is formed into the duct 85 of FIG.25, the flap 79 overlaps the outside of the joint and is bonded to theouter surface of the sheet 80. This effectively seals the passagewaydefined by the duct 85, and may be used as the sole attaching means tohold the edge portions of the pattern together. In the latter event, theedge members (such as wires 38 and 39 of FIG. 15) may be omited.Normally, prior to attachment of the flap 79, the adhesive 83 on theflap is protected by a removable strip of the type normally applied topressure-sensitive adhesives.

In the embodiment of FIG. 26, a separate strip of adhesive tape 86 isapplied to the duct 87 after the support members have been benttransversely to define the fluidv passageway. The adhesive tape 86accomplishes the seal for the duct 87, overlapping the outer sheet 88 atthe joint and holding together the adjacent edge portions of the joint.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited snlelv by the appended claim I claim:

1. The method of providing a fluid conduit comprising the steps ofarranging a plurality of elongated members so as to define asubstantially rectangular pattern having open spaces therein,

positioning a substantially flat and rigid strip at either end of saidpattern to form a part thereof,

holding said elongated members and said strips together in said pattern,

superimposing a flexible sheet on said elongated members to cover saidopen spaces,

then bending said elongated members, said sheet and said strips in adirection generally transverse to said strips so as to cause said stripsand elongated members to be given a permanent set such that oppositeedge portions of said pattern are brought into adjacency and said sheet,said strips and said elongated members define a passageway collectivelytherethrough and said strips extend around the ends of said passageway,

and attaching together said edge portions of said pattern when so bent,

thereby providing a fluid conduit.

2. The method of providing a fluid conduit comprising the steps ofinterposing a plurality of substantially parallel wires between aduality of flexible sheets,

extending opposite edges of said sheets over sheet metal stripssubstantially parallel to said wires,

bonding said sheets to said wires, to said strips and to each otherintermediate said wires so as to form a unitary assembly,

then bending said wires and said strips transversely so as to give thesame a permanent set and to bring opposite edge portions of saidassembly into adjacency,

thereby to define a passageway,

and then attaching said edge portions together and effecting a seal forsaid passageway.

3. The method as recited in claim 1 in which a nonharde'ning adhesive isapplied to said sheets for effecting said bonding.

4. The method as recited in claim 1 in which said strips and wires arebent to different predetermined configurations to provide differentshapes at the opposite ends of said passageway.

5. The method of providing a fluid conduit comprising the steps ofproviding a duality of substantially rigid flat strips in spacedparallelism,

positioning a plurality of elongated members intermediate said stripswith said elongated members being in spaced parallelism and said stripsand said members defining a substantially rectangular pattern in whichthe opposite end portions of said elongated members and said stripsextend to opposite edge portions of said pattern,

superimposing a first flexible sheet over said pattern on one sidethereof,

superimposing a second flexible sheet over said pattern on the oppositeside thereof,

bonding said first and second sheets to said elongated members and tosaid strips and to each other so as to provide a unitary assembly,

then bending said elongated members and said strips transversely so asto give said elongated members and said strips a permanent set and tobring said opposite edge portions of said pattern into adjacency,

thereby defining a passageway,

and then attaching said edge portions together and effecting a seal forsaid passageway.

6. The method as recited in claim 5 in which in attaching said edgeportions together and effecting a seal for said passageway a flexiblestrip of sheet material is bonded to the exterior of said passageway atthe vicinity of said edge portions.

7. The method as recited in claim 5 in which for attaching said edgeportions together and forming a seal said first flexible sheet isextended beyond said pattern at one of said edge portions to provide astrip of flexible material,

said elongated members and said strips are bent so that said firstflexible sheet is on the outside of said passageway,

and said strip of flexible material is caused to overlap the adjacentexterior surface of said first flexible sheet and is adhesively securedthereto.

8. The method as recited in claim 5 in which said strips and saidelongated members are bent to different predetermined configurations toprovide different shapes at the opposite ends of said passageway.

9. The method as recited in claim 5 in which attaching said edgeportions together and effecting a seal for said passageway a strip ofadhesive tape is attached to said passageway at the vicinity of saidedge portions.

References Cited UNITED STATES PATENTS 2,371,042 3/1945 Fogg 138-1382,426,058 8/1947 Scogland 156-218 2,625,499 1/1953 Nebesar 1381782,937,664 5/1960 Plummer 138-128 3,212,529 10/1965 Ullrnan et al.138-141 3,422,525 1/1969 Jeppsson 138-156 1,675,316- 6/1928 Russell138-109 1,981,413 11/1934 Goodfellow 138-120 1,993,965 3/1935 Huck etal. 138-128 2,371,556 3/1945 Steffens et al. 138--119 2,858,854 11/1958Daggett 138124 (Other references on following page) 1 1 1 2 UNITEDSTATES PATENTS 6 CHARLES W. LANHAM, JR., Primary Examiner 3,251,382 5/1966 Tatsch 138151 D. CRANE, Assistant Examiner 3,369,568 2/1968- Daviset a1 138--168 3,496,965 2/1970 Hureau 138--123 US. Cl. X.R. FOREIGNPATENTS 5 7 A; 1 -218 560,270. 3/1944 Great Britain 138-56

1. THE METHOD OF PROVIDING A FLUID CONDUIT COMPRISING THE STEPS OFARRANGING A PLURALITY OF ELONGATED MEMBERS SO AS TO DEFINE ASUBSTANTIALLY RECTANGULAR PATTERN HAVING OPEN SPACES THEREIN,POSITIONING A SUBSTANTIALLY FLAT AND RIGID STRIP AT EITHER END OF SAIDPATTERN TO FORM A PART THEREOF, HOLDING SAID ELONGATED MEMBERS AND SAIDSTRIPS TOGETHER IN SAID PATTERN, SUPERIMPOSING A FLEXIBLE SHEET ON SAIDELONGATED MEMBERS TO SAID OPEN SPACES, THEN BENDING SAID ELONGATEDMEMBERS, SAID SHEET AND SAID STRIPS IN A DIRECTION GENERALLY TRANSVERSETO SAID STRIPS SO AS TO CAUSE SAID STRIPS AND ELONGATED MEMBERS TO BEGIVEN A PERMANENT SET SUCH THAT OPPOSITE EDGE PORTIONS OF SAID PATTERNARE BROUGHT INTO ADJACENCY AND SAID SHEET, SAID STRIPS AND SAIDELONGATED MEMBERS DEFINE A PASSAGEWAY COLLECTIVELY THERETHROUGH AND SAIDSTRIPS EXTEND AROUND THE ENDS OF SAID PASSAGEWAY, AND ATTACHING TOGETHERSAID EDGE PORTIONS OF SAID PATTERN WHEN SO BENT, THEREBY PROVIDING AFLUID CONDUIT,